Refrigerating apparatus



May 10, `1938.` G C PEARCE' 2,116,909

REFRIGERAT ING APPARATUS WIJ B`Y QV ATTORNEYS 10, 1938. Gl Q PEARCE2,116,909

` REFRIGERATING APPARATUS Filed Jan. 3U, 19.34 8 SheetS-Shee'lI 2 A NgWil.'

ISI

May 10, 1938. G. C. PEARCE 2,116,909

REFRIGERATING APPARATUS Filed Jan. BO, 1954 8 Sheets-Sheet 5 May l0,1938. G, PEARCE QQ REFRIGERATING APPARATUS Filed Jan. 30, 1934 8sheets-sheet 4 May 10, 1938. C;l C, PEARCE 2,116,909

REFRIGERATING APPARATUS l Filed Jan. 30, 1954 8 Sheets-Sheet 5 May 10,1938. G. c. PEARCE 2,116,909

REFRIGERATING APPARATUS Filed Jan. 30, 1934 8 Sheets-Sheet 6 mom/WAH May10, 1938. G. c. PEARCE REFRIGERIATING APPARATUS Filed Jan. 30, 1934 8Sheets-Shea?l 7 ...mmm

REFRIGERATING APPARATUS Filed Jan. 30, 1954 8 Sheets-Sheet 8 ITINI HH gtff l i zw m f 21;;

Patented May 1o,f 193su 2,116,909

UNITED STATES PATENT oFFicE REFRIGERATING APPARATUS George C.v Pearce,Dayton, hio, or to General Motors Corporation, Dayton, h10, acorporation of Delaware Application January 3%, 1934 Serial No. 3108.994

4 Claims. iCl. 20o-31E;

This invention relates to refrigerating appa-1 ratus and moreparticularly to pressure operated refrigerator control switches.

It is an object of my invention to provide an 5 improved switchmechanism for refrigerating apparatus, said switch mechanism beingprovided. with a temperature adjusting means` providing continuouscycling above and below freezing; temperature, and with a defrostingmechanism i0 which is automatically rendered ineil'ective when theproper temperature is reached, together with device and the i animproved overload means for the electric cirs defrost device; cuit inwhich a iinger manipulatingdevice server. Fia. es a diagrammatic View ora reirgerat both for shutting the refrigerator on and oi! as ing systemshowing diagmliimeleolly "the Eleloli,

. is a sectional View along the line @mii ci s a sectional View aiongthe 'im-i in i5 well as for resetting the overload device and serv@ the'terminal looX. the vlooi Switch. the door light? l5 lng as anindicating means for indicating the er the electrical erelS;

condition of the` overload means. f- Fig. 'il is a sectional Viewshowing the sonnen#u y, It is anptther object of my invention to providetion between a 'terminal the terminal nog and a switch for arefrigerating system provided with, a set of contacts in the switch;

parts that may be easily manufactured, assernn Fig. is a diagrammaticView of a reirigerat- .5G

bled, and repaired, and so arranged that the ing system illustrating amodification ci my inmanually manipulatable control devices and thevention; indices therefor may be symmetrically arranged. Fis 13 is a topView with the Cover removed ci It is another objectof my invention toprovide the refrigerator Switch Shown in Fig. 12;

.5 an improved switch wherein a terminal/box is Flg- 1418 a SectionalView along the line lil-J4 g5 directly connected with the switch butwhich preof F18. 13; vents ready access to the switch mechanism while 2F18- 15 is a Sectional View along the line l5-i 5 at the same time itprovides easy access to the of F18. 13; terminal connection of theswitch and provides F18- 16 1S a Sectional View along the line lG--l aplace for a direct current adapter as well as 0f P18113; 30 additionalterminals for connection to the other Fis. 171s a Sectional view alongthe line Il-,il accessories such as a door switch and light. of Fig. 13;

Further objects and advantages of the present f F18'- 18 1S a SectionalView elong'the lino l8-l8 invention will be apparent from the followingdeof Fig. 13;

scription, reference being had to the accompany- F18- 19 1S o SectionalView along the line |9-l9 35 ving drawings, wherein. a preferred form ofthe of F18- 14;

present invention is clearly shown. Fig. 20 is a sectional view alongthe line 2li-10 In the drawings: of Fig. 19; y Fig. 1 is a top view ofone form of my improved 11115.21 iS o View Showing a fragment of theswitch with the terminal box removed; y terminal connections in the topcover; and 40 Fig. 2 is a sectional view along the line 2 2 of Fis. 22isa sectional view 'along theline 22-22 Fig. 3; of Fig, 19.

Fig. 3 is a sectional viw along the line l-I of Referring to thedrawings and more particu- Fig. 1; larly to Fig. 10, there is shown arefrigerating sys- Fig. 4 is a sectional view of the 'right hand temcomprising a compressor 30 for compressing 45 portion of Fig. 3, takenupon a line corresponding the refrigerant and for forwarding the comtothe portion of the section line 2-2 upon the vpressed refrigerant to acondenser 3| where the -right side of Fig. 3, and showing the thermalcompressed refrigerant is condensed and collectoverload means andratchet wheel in the position ed in a receiver I2. From the receiver 32the nl it assumes after being tripped by an overload in liquidrefrigerant iS forwarded throuhe Supply 50 the electric circuit; conduity33 to an expansion valve or other suitn Fig. 5 is a sectional Viewsimilar to Eig, 4 but able restricting means 34 which controls thesupdiiering in that it shows the mechanism thermal ply of liquidrefrigerant to an evaporator 35 looverload mechanism after beingmanually tripped cated within the food compartment of the reto open theelectric circuit; frigerator 36 where the evaporator absorbsheat causingthe liquid refrigerant. to vaporiae and he returned to the compressorThe compressor is driven by an electric motor 3l under the control oi athermostat Sil in heat exchange lation with the evaporator rEhethermostat 38 is connected by a tube 3Q to the pressure responsive snapacting switch means /l-Q having a set of switch contacts fl which areconnesl d to the terminals ft2 and located in fiinal box [lil shown in9. he ter- 1 connected by an electrical conductor 5 'to one oi thelead-ins of the motor, while the terminal S3 has one electricalconductor to leadto a source of electric energy, while another 'lconductor di leads from the terminal refrigerator light i8 locatedwithin compartment of the cabinet m" e door minal is also connected byelectrical conbox :3o. rEhe terminal 5@ is also connected by anelectrical conductor to a door switch which is operated by opening andclosing oi the rei igerator cabinet door so as to cause the light @illee lit when the door is open. The door switch is also connected by anelectrical conductor ce to a terminal iid located. in the terminal boaThis terminal is also connected by electrical conductor to theelectrical conductor which connects the second lead-in oi the elec-'trical motor dl to a side of the supply line. "ihe conductors :il and lare grouped together within an insulating covering @d which leads fromthe terminal box lf3 to the door light Cil. The electrical conductorsd5, fili, and are grouped together within insulating covering @l whichleads from the terminal box to the electric motor 3l and the supplycircuit. The electrical conductors and are grouped together within aninsulating covering which leads from the terminal box to the door switch5l.

rilse 'terminal box [ld rests upon the frame member extending across thetop of the cabinet and is fastened thereto by suitable screws G0. Theterminal box ld is provided with a removable cover which is fastenedthereby by a screw Within the terminal box there is provided partitionsiill which divide the various terminals from each other. Additionalspace is provided adjacent the terminals d2 and d3 to receive a directcurrent adapter it one is required. Resting within a notch in the framemember immediately beneath the terminal box is the switch mechanism.This switch mechanism is connected to the terminal box Lid and to theterminals d2 and. 43 by screws 00 and 69 which extend through theterminals 42 and 13 and are threaded into the brackets lli and ll of theswitch mechanism. A third screw 'l2 extends from the terminal box and isthreaded into an ear i3 formed on the framework of the switch mechanism.

Upon the front of the cabinet immediately in front of the switchmechanism there is provided an escutcheon plate 'M provided with anindicating knob 'l5 having an arrow cooperating with the dial lli formedon the escutcheon plate in order to provide manipulating and indicatingmeans for temperature regulation. At the left side of the escutcheonplate there is provided a rectangular aperture Tl having the fingermanipulating device 'I8 projecting therefrom which cooperates with theindications On and Off on the escutcheon plate in order to indicate thecondition or the overload means as to whether the overload means is inclosed or open circuit position to turn the refrgerating system. 0n or0d.

' effective position, thus permitting th the "ri-nt side of theescutcheon plate 'lil in a symmetrical arrangement with the lrnob l andthe manipulating device there provided a rectangular aperture lllthrough winch projects a ringer manipulating and indicating device d@winch cooperates with the desig ation rise above Lreeaing melt thererornand after ture limit is reached s deirosting, this device order Ytoper'n be reto.

ing system to resume normal opera- Refer now more particular .t side orr there is shown at the rigT open at the top (as viewed in of a suitablestructural insulat as hard rubber or a phenol condeLsation in. such asBakelite, stened to the bof rivets C@ is a braclret of; l' whichsupports the let side o ni in as viewed in l. C tremities of thisbracket by E -shaped bracket SSI which si j connected at its lower endto tde tube leads to the thermostat bulb Sill located food compartment.r)The lower ot the lc is fastened to the L--shaped bellows suppo ingbracket E@ by a nut di. in order to prevent excessive expansion o thebellows there is provided an inverted L-shaped fiat metal stop member 92which is provided with projections llt at one end which extend throughslots @il in. the bellows supporting member il@ while the other end, asbest shown in Fig. 8, is provided with an aperture or slot Q5 whichreceives a tongue @o through which extends a cotter pin @l for holdingthe bellows stop in place.

A portion QQ o the bracket extends downiected to t screws ik.

"wardly and is provided with a tongue lll@ which surfaces of a bellows`follower l0@ formed of heavy sheet steel or brass. rFhis bellowsfollower E03 is held in place by a cotter pin mi which extends throughthe tongue U00. The bellows follower |03 is provided with a depressionin one side which receives a conical pin H05 which extends from themovable end oi the bellows 90.

At one side, the bellows follower l03 is provided with an ear il'lGextending at right angles which is connected to a tension regulatingspring lill. This tension regulating spring is connected at its lowerend to a transverse lever |08, better shown in Fig. 8, which is pivotedupon a pin H09 at its intermediate point to the bracket 08. The otherend of the lever |08 is pinned to the member H0 which is threaded uponan adjusting screw l provided with a splined head H2 upon which thetemperature regulating knob 15 is mounted. By turning the temperatureregulating knob, the tension of the spring |01 is varied in order tocontrol and vary the expansion of the bellows 90. By this arrangementthe size or" the regulating screw and the spring may be made small sincethe use of the lever |08 permits of considerable variation in travelbetween the member ||0 and the lower end of the spring l 01. Thisarrangement also avoids the binding action found in most otherarrangements for temperature adjustments.

The bellows follower |02 is also provided with a hard rubber or Bakeliteinsulating arm or extension ||3 molded thereon which insulates thebellows and the bellows follower from the switch mechanism and which isprovided at its extrem/ity with a pair of V-shaped notches ||4 whichreceive the knife edges ||5 formed upon the legs of a `U-shapedsecondary lever I5 which formsa, part of a double toggle snap acting l0mechanism. 'I'he U-shaped secondary lever is provided at the opposite orclosed end with a T-shaped member ||1 which extends through a /slot inthe end portion of the U-shaped member .and is provided with an eyelet||8 to which is A connected the tension coil spring ||9. The other I endof this tension coil spring is connected t0 an upstanding portion of acontact member |2| of irregular shape which is pivoted upon the pin |22to a bracket |22 riveted to the wall 20 of the box 25. This contactlever is also provided with integral stop portions |24 and |25 whichlimit the movement of the closed end of they U-shaped secondary leverH5. 'I'he contact lever |2| also has another arm |22 which car- 25 jriesby a swivel pin arrangement a contact bar |21 which bridges the contacts4| in order to complete the electric circuit.

As stated before, the -contact 4| nearest the open side'of the box 25 isprovided with a thread- 30 ed bracket 1| for connection with the screw52 extending from the terminal 42 and the terminal box 44 and in thisway electrical energy is supplied to these contacts. Extending from theopposite contact 4| is a heater coil |22 which extends around a pin |29having a ratchet wheel |20 fastenedthereto by a fusible material, suchas solder. This pin `.|29 is provided withi a threaded portion whiclipasses through the wall of the box 25 and is threaded into the nut |2|seated in the recess in the 'opposite side of thel bottom wall of thebox 25. 'I'he otherend of the heater .coil |28 is connected to one of aset of overload contacts |22, while the other contact of this set isconnected to the threaded bracket l 12 which is connected by the 'screw29 to the terminal 42 in the terminal box 44.d

'I'he contacts |22 are adapted to be bridged by the overload contact bar|22 whichis connected by a pin and springy connection to the lower endof an'overload lever |24 pivoted on a pin |25 /fixed in the bottom wailof the box 25.` This overload lever |24 is normally held in a verticalposition such as that shown in Figs. 1 and 2 by a slide bar |22 whichextends through a slot in the lower end of an arm |21 of a bracket |22and which has its other end guided by the arm |29 at the oppositev sideof the bracket |22. This slide bar is provided on its bottom side with alight leaf spring member |42 which engages the ratchet-wheel |20 inorder to prevent the overload rcontact lever |24 from moving to opencircuit position which -isv illustrated in Fig. 4. 'I'he overloadcontact lever"|24 is yieldingly urged to open circuit position by thetension spring 14| which extends from the overload contact lever |24tosthe arm |21; When an excessive electrical current passes through theheater coil |22 for a sufficient length of time the pin |29 is heatedsuiiiciently to melt the fusible binder thereby permitting the ratchetwheel |22 to turn, thus releasing the leaf spring |40 and the slide bar|25 in order to permit the overload contact lever |22 to move to opencircuit position under the tension of the overload spring |4|. The slidebar |22 is provided with bent-up lip or `tongue |42 which normally isadapted to engage a shoulder upon the overload contact lever |24. Thisslide bar |25 is also provided with a second bent-up lip or tongue |42which extends in the opposite direction. When it is desired to shut offthe refrigerator the overload finger manipulator 12 is moved to the leftas viewed in Figs. l and 2, thus moving to the right a hookshaped slidebar |44 as shown in Fig. 5 so that a cam |45 on its bottom edge engagesthe upper surface of the lip |42 so as to move the free end of the slidebar |25 downwardly to disengage the lip |42 from the overload contactlever |24. This hook-shaped slide bar 44 is yieldingly urged to the leftby the tension coil spring |45 in order to hold it against the lowerprojecting portion |41 of the iinger manipulator 12. The fingermanipulator 18 is pivoted upon the pin |48 to a Wall of the box 85.

In order to reset the overload means there is provided a reversedL-shaped lever |49 which is pinned to the lower projection |41 of thefinger manipulator 18. This lever |49 is yieldingly urged fingermanipulator 19 is moved to the right, as

viewed in Figs. 1, 2, 4, and 5, the nose of the lever |49 engages theinclinedsurface of the tongue |5| which forces its free end upwardlyinto engagement with the laterally extending insulating member |52 whichextends from a portion of the main contact lever |2|. This engagementmoves the main switch contact bar |21 to open circuit position during'the time at which resetting operation takes place. In addition to.engaging the insulating member |52, the link |48 also moves the @verloadcontact lever |24 to its vertical position as viewed in Figs.- l and 2.This permits the tongue |42 oi the slide bar |25 to again engage itsshoulder upon the overload contact lever |24 if it has been in theposition shown in Fig. 5. If the overload mechanism has been in theposition shown in Fig. 4, which it assumes when tripped by an overloadcurrent, the overload contact lever 24 will engage the turned-up lip |52at the adjacent end of the bar |22 and pull the bar to the left asviewed in Fig. 4 so as -to permit the leaf spring |40 to again engagethe ratchet wheel |22 as yshown in Fig. 2.. By moving the main switchcontact bar |21 to open position during the resetting operation,forcible operation of the refrigerating apparatus under overloadconditions by holding the finger manipulator in resetting position atthis time is prevented. Y

The bottom of the lever or link |49 is provide with a locking shoulder|15 which is adapted to engage the arm |29 of the bracket |28 upon whichthe link |49 normally rests by gravity in order to prevent anyone fromopening the main switch contacts 4| and |21 by moving the fingermanipulator toresetting position. In vthe normal resettingopefrationythis shoulder 15 is not engaged because the free end of thelever or link I 49 is raised by the camming surface of the tongue |51`thus causing the shoulder |15 to clear the bottom lportion'of the slotin the arm |29 of the bracket |22 through which extends the link |49.After the resetting operation is completed, the free end of the link |49is out of contact with the camming surface |5| and rests by gravity uponthe bottom of the slot in the arm |29. Thus, after resetting,

any movement of the link |49 toward the camming surface lill will bestopped by the engage-- ment oi' the shoulder H5 with the portion of thearm i351) below the slot. 'By preventing the contact of the end o1? thelink i559 with the camini-ng surface at this time the opening of themain contacts which is depend-ent upon the coaction oi` the end o thelink with the camming rac ning and closing adjusted. by the s the irontwall of 1apted at its lower end nber which exten contact lever movementoi this main con.-

t lea s g ibi' engages the on 'he hexagonal portion of the dierentialscrew iii@ in order to prevent unintended move- 4ereoi. '3y so doing,the closing pressure and temperature of the main Switch contacts isvaried independently oi the temperature regulating or range adjustingmeans.

ln order to provide' means for derosting the refrigerator, thedefrosting finger manipulator 0@ is pivoted to an ear lli@ formed at oneend of the bracket Sill. Extending from one side of this 'fingermanipulator is a threaded pin itl which moves bodily with the fingermanipulator S0. The threaded pin itl is surrounded by a compression typecoil spring MS2 which is held between a splined adjusting nut M33threaded upon the pin Mii and spring follower l i which is slidablymounted upon the free unthreaded end portion of the pin itl and whichpresses against knife edges formed upon the free end portion of a togglelink |105 pivoted by means of a pin lb@ to a toggle supporting bracketE01 riveted to a portion of the bracket 00. This toggle link has bentportions which receive a roller iitl which s pinned to this toggle link|105. @is roller is adapted to bear upon a projecting portion it@ of-the bellows iollower i03 when the iinger manipulator 00 is moved todefrosting position. When the finger manipulator is moved to defrostingposition, this compression toggle link mechanism exerts an additionalresilient pressure upon the bellows follower |03 which opposes theexpansion of the bellows and which thereby requires an additional orhigher pressure within the bellows and the thermostat bulb 38 and,consequently, a higher temperature of the thermostat bulb 38 and theevaporator 35 before the main switch contacts will be moved to closedcircuit position to enable the refrigerating apparatus to resumeoperation. When this required high pressure and temperature is reachedthe upward movement of the bellows follower |03 will also move theroller |68 and the toggle link |65 upwardly across the dead centerposition so that it returns to its upper inactive position in which theroller |68 is out of the path of the normal movement of the bellowsfollower |03 and rests against a portion of the bracket 98. In this way,this snap acting defrosting mechanism is returned automatically toinactive or ineiective position upon completion oi a defrosting cycle.If it is desired to discontinue a defrosting cycle at any time duringthe cycle, the finger manipulator 80 can be moved to ineffectiveposition merely by moving the finger manipulator to the left as viewedin Figs. 1, 2, and 3.

In Figs. 12 to 22, a modification of my invention is shown.

Referring now more particularly to Fig. 12, there is discloseddlagrammatically a source of contact 'beat 'um .icli is connects to setcontacts the contacts EEE, tends to a starting winding L.; locatedsealed unit From the electrical. conductor 2M extends an electricalconductor 225i which connects to an electi'omagnet which operates uponan armature arm which when attracted is adapted to pivot about. thepivot point 223 to close the circuit to the contacts ii. Theelectromagnet 221i is also connected to an electrical conductor 2 oneend of which leads to the running win. ng "lii located. within thesealed unit 2l@ and for a part of an electric motor 226.

`llie electrical conductor i is also connected to a stationary contact22'?! v sich cooperates with the movable contact 252 fixed to theU-shapec. bimetal member 2li. other ends o the an eectilcal conductorrunning winding and the starting winding 2i@ are connected by anelectrical conductor to a control switch located within a cooling unitor evaporating means within the iood compartment 23H of a refrigerator.This control switch 220 is operated by a thermostatic bulb 232 locatedin contact with the bottom of the evaporating means 230.

The cooling unit 230 absorbs heat from the food compartment 23| andvaporizes the refrigerant which is withdrawn from the cooling unitthrough a suction line 233 by a compressor 234 located within the sealedunit 2|9 and directly connected to the electric motor 226. Thecompressor 234 compresses the refrigerant and forwards the compressedrefrigerant to a condenser 235 Where the compressed refrigerant isliqueed and forwarded through a supply conduit 336 under the control ofa suitable restrictor 331 to the cooling unit 230.

When refrigeration is required, the thermostatic bulb 232 becomessufliciently warm to cause the control switch 229 to close, thus closingthe electric circuit and permitting a heavy surge current to flow fromthe source of supply 200 through the electrical conductor 20| and fromthe contact 20`2 through the contacts 205, and the lever 204 to thecontact 206, through the heater 201, and the U-shaped bimetal member 2||and through the electrical conductor 2 I4 and the conductor 220 throughthe electromagnet 22| and the electrical conductor 224 as well asthrough the running winding 225, the electrical conductor 228, thecontrol switch 229, to the source of supply. This surge current isinsumcient to cause the overload to heater'20l to open the contacts 202and 206 but is sufficient to cause the electromagnet 22| to attract thearmature 222 to close the circuit to the contacts 2|6 in order to permitelectric energy to ilow through the electrical conductor 2|5, contacts'2|6, and the conductor 2|1 to the starting Winding 2|8. By per-.mitting the iiow of electric energy through starting winding andrunning winding, the electric motor 226 will be started.

This abnormal surge current causes heating within the U-shaped bimetalstrip 2|| which after suiiicient heating moves to close the contacts 2I2 and 221. This provides a shunt around the electromagnet 22| andweakens the attraction between the electromagnet and its armature 222,thus permitting the armature 222 to drop and to open the startingwinding circuit at the contacts 2|6 thereby connecting the off supply ofelectric energy to the starting winding 2|8. The heating action of theelectric current through the leg 2|0 of the U-shaped bimetal member 2||is insufilcient to maintain the contacts 2|2 and 221 in closed positionand these contacts open, thus causing the current to the running windingto -flow through the leg 2|3 to conductor 2|4 and the conductor 226through the electric magnet 22| to the starting winding 225. However,the amount of current passing through the electromagnet 22| and therunning winding 225 is insuiilcient to cause attraction of the armature222. The circuit thus operates under this condition until the thermostat232 becomes suiiiciently cold to cause the control switch to be openedto open the electric circuit. This permits the U-shaped bimetal member2|| to cool and to again` assume starting position. Instead of beingconnected in the circuit as shown in Fig. 12, the entire overload meansmay be placed in series with the electric conductor 224 and the runningwinding 225 where the overload means may be made more sensitive tooverloads during the running period of the driving motor and not besubject to starting winding currents. In this way more sensitiveoverload protection may be provided.

Referring now more particularly to Figs. 13 t0 22 inclusive, there isshown a more complete embodiment of the Acontrol switch 228. The controlswitch 229 is provided with a lower housing 238 and an upper housing orcover 236, each of which ismade of a suitable'structural insulating ma'terial, such as hard rubber. 'I'he housing is supported upon a crossstrip 231 extending irom one side to the other of the cooling unit 238.A screw v238 fastens the housing to this cross strip 231 by means of anut 239 which fastens the lower housing to the cross strip and an upperknurled nut 248 which fastens the upper housing 236 to the lower housing235 and the cross strip 231.

Fastened to the lower housing 238 by screws 24| and 242 is abracket 243which is connected to an L-shaped bellows'support member 244 by thescrews 245. A metal bellows 248 is fastened to this bellows supportmember by a nut 241 and is connected to the thermostat bulb 2 32 by atube 248. The bellows 248 is protected from', excessive expansionV by aninverted L-shaped at metal stop member 256 which is provided with prongs28| at one end which engage slots in the L-shaped bellows supportingmember 244, while the other end is provided with an aperture or slotwhich receives a tongue 282 provided with a cotter pin 263 for fasteningthe bellows stop to the bellows supporting member 244.

The metal bellows 248 is provided at its upper end with a. conicalprojection 288 which engages a recess in a bellows follower 288 which isprovided with an aperture which receives a tongue 251 provided with acotter pin 258 for pivotally fastening the bellows follower to theprojection of the bracket 243. Upon the freely movable end of thebellows follower 256 is an insulating arm or extension 259 which isprovided with a pair of V-shaped notches 260 which receive a pair ofknife edges formed upon the end of the leg of the U-shaped secondarylever 26| which forms a part of a double toggle snap acting mechanism.This secondary lever is provided with a T-shaped pin 262 which extendsthrough an aperture in the closed end of the secondary lever and isprovided with an eyelet 263 to which is connected a tension-like togglespring 264 having its other end connected to a projection 265 whichextends up between the parts of the insulating arm 259. The projection265 is struck up from a contact lever 266 which is pivoted at 261 to thelower housing 235. This contact lever is provided with stop portions 268and 269 as well as an extension 210 which is pivotally connected tocontact bar 21| which when in closed position serves to bridge a set ofcontacts 213 which are fastened to the lower housing 235.

The contact lever 266 is also provided with a second extension 215formed of an insulating material which is adapted to contact with adifferential adjusting screw 216 which is provided with a hexagonalportion 211 cooperating with a light leaf spring 218 for preventingevaporation from altering the differential adjustment and causing thedifferential screw 218 to be turned thereby. This differential screw 218limits the opening movement of the contact lever 266 and thereby variesthe differential between the opening and closing of the switch contacts.

A range adjustment is also provided. The bellows follower 256 isprovided with an ear 288 to which is connected a tension spring 28|having its lower end connected to a lever 282 which is pivoted at itsopposite end by a screw 283 to the bracket 243. At an intermediate pointthe lever 282 is provided with a pin 284 which connects the lever to anadjusting screw 285 provided with a ilange nut 286 at its upper endwhich may be employed to raise or lower the lever 282 in order to varythe tension upon the spring 28| in order to control and regulate theexpansion oi the metal bellows 246.

The switch is also providedwith a defrosting mechanism which is pivotedupon the screw 24|. This defrosting mechanism comprises a member 288pivoted upon the screw 24| yariel having a threaded extending portionprovided with an adjusting nut 288 which bears against one end of a.compressing toggle spring 288 which surrounds the threaded extendingportion. The other 'end of the toggle compression spring 288 cooperateswith the toggle link 28| which is pivoted by s pin 282-to a bracket 283which is riveted to the bracket 243.` This toggle link 28|is providedwith a roller 284 which is adapted to bear upon the bellows follower 288when in its effective or actuating position as shown in Fig. 19. Thissnap acting mechanism through the roller 284 interposes an additionalresistance to the expansion of the metal bellows 248 and requires asumciently high temperature, such as 40 F. to permit defrosting of theevaporator before sumcient pressure will be produced in the bellows 246to overcome this additional resistance and move the contact bar 21| toclosed circuit position. In so doing, the bellows -follower movesupwardly thereby moving the roller 284 and the snap acting mechanismupwardly to inactive position wherein the roller ref mains ont ot thepath of movement of the bellows follower 256. The upward movement oftlie toggle linl; is stopped by the bracket 2533.

The snap acting defrosting mechanism is therefore automatically turnedoff when the proper temperature is reached. However, manual rneans inthe form of a linl is connected to the enm tension of the member 2&8 andtlie toggle lint", 29E at the end ci the compression spring 2Q@ i; orderto initiate a deirosting cycle. This lint.: is provided with extensionwhich extends to the iront of tbe cooling unit. l'n order to initiate adefrosting cycle this extension 29B is pushed rearwardly, thus moving'the defrosti'ig incollanism into its position with the roller bearingupon the bellows follower any time bea fore completion ol? thedetre-sting cycle it is desired to resume normal operation immediately,the en tension 296 may be pulled out to remove the roller 2Q@ 'from thepatti oi the bellows follower and to move the deirosting mechanism toretracted position in order to permit the refrigerating system to resumenormal operation immediately.

The top cover 238 is provided with terminals 298 and to which areconnected the electrical conductor 228 and the electrical conductor Sil@which lead respectively to the electric motor and the source of supply.These-terminals 298 and 29S? are provided with spring portions which areadapted to engage extensions Sill extending from the switch contactsZilli. in this way a convenient connection is provided.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to loe understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

l. A switch including means responsive to a predetermined ow of electricenergy through an electric circuit for opening the electric circuit,resetting means for said rst mentioned means for moving the rstmentioned means to closed circuit position iron: open position, andlocking means ineffective .ig the moving' of the reattacco setting meansfrom open position to closed position for preventing the movement oitl'ie resetting means to closed position after the resetting has beenreset.

2. ./i switch including means responsive to a 5 predetermined flow oelectric energy through electric circuit for opening tlie electric ci`1esetting means for said :first mentioned nl 1 r moving the rstmentioned circui' liosition from open "osi o ening the electral ci'.' coperation, and locltinL ment oi the resetti. c if; after being reset inorder to prevent tb. of the electric circuit,

3. A switch including pl switch contacts arranged in c means `foropening and closing a switch contacts, overload means overloadconditions for opening a second set contacts, said overload means havingreset means for closing the second set of contacts, resetting meansbeing provided with meel holding open the nrst set oi contacts dvi' Aresetting of the second set oi contacts, said overload means beingconstructed to prevent the Opern. ing of the rst set or" contacts by theresetting means while the second set of contacts are in reset position.

4. A switch including means responsive to a predetermined now ofelectric energy tlirougli an electric circuit for opening the electriccircuit, 3f resetting means for said rst mentioned means for moving thenrst mentioned means to closed circuit position from open position, saidresetting means having protecting means for opening the electric circuitduring the resetting of said first 40 mentioned means, said resettingmeans being constructed to prevent the actuation of the protecting meanswhen the first mentioned means is in reset position.

GEORGE C. PEARCE. 45

